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TEKNOLOGI MEMBRAN
Nur Istianah-T.Membrani-2016
is a VERY THIN film that allows some types of matter to pass through while leaving others behind
Membran= materials which have voids in them letting some molecules pass more conveniently than some other molecules
semi-permeable membrane
Retentate
PermeateMembrane
Feed
Konsep dasar
Nur Istianah-T.Membrani-2016
Driving force :
3. Voltage difference,
1. Pressure difference
2. Concentration difference
4. Temperature difference,
RO UF MF Pervaporation
Dialysis Membrane extraction
Electrodialysis
Membrane distillation
Nur Istianah-T.Membrani-2016
0.0001 0.001 0.01 0.1 1 10 100mm
hairCrypto-sporidium
smallest micro-organis
m
polio virus
Suspended solids
Parasites
Bacteria
Org. macro. molecules
Viruses
ColloidsDissolved salts
Sand filtration
Microfiltration
Ultrafiltration
Nanofiltration
Reverse Osmosis
ZW500: 0.04 umZW1000: 0.02 um
TYPES OF PROCESSES
Nur Istianah-T.Membrani-2016
Range of membrane capabilities for food application
Nur Istianah-T.Membrani-2016
REVERSE OSMOSIS/ hyperfiltration
Nur Istianah-T.Membrani-2016
REVERSE OSMOSIS
• only remove some suspended materials larger than 1 micron
• the process eliminates the dissolved solids, bacteria, viruses and other germs contained in the water
• only water molecules allowed to pass via very big pressure
• assymmetric type membranes (decrease the driving pressure of the flux)
• almost all membranes are made polymers, cellulosic acetate and matic polyamide types rated at 96%-99+% NaCl rejection
Nur Istianah-T.Membrani-2016
REVERSE OSMOSIS
• Applications in food industries:– the concentration of whey from cheese
manufacture (the most use) – concentrate and purify fruit juices (Robe, 1983),
enzymes, fermentation liquors and vegetable oils– concentrate wheat starch, citric acid, egg white,
milk, coffee, syrups, natural extracts and flavours– to clarify wine and beer– to demineralise and purify water from boreholes or
rivers or by desalination of sea water.
Nur Istianah-T.Membrani-2016
REVERSE OSMOSIS
• ‘dealcoholisation’to produce low-alcohol beers, cider and wines,
• recovery of proteins or other solids from distillation residues, dilute juices,
• waste water from corn milling or other process washwaters.
Nur Istianah-T.Membrani-2016
REVERSE OSMOSIS• future directions:
– municipal and industrial waste treatment– process water for boilers – de-watering of feed streams– processing high temperature feed- streams
Nur Istianah-T.Membrani-2016
MICROFILTRATION
• largest pores • a sterile filtration with pores 0.1-10.0 microns• micro-organisms cannot pass through them• operated at low pressure differences• used to filter particles. • may or may not be assymmetric • lower pressures than RO
Nur Istianah-T.Membrani-2016
• wide array of applications:– parenterals and sterile water for
pharmaceutical industry– food & beverages – chemical industry– microelectronics industry– fermentation– laboratory/analytical uses
MICROFILTRATION
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
MICROFILTRATION
• applications in the near future:– biotechnology (concentration of biomass)– diatomaceous earth displacement– non-sewage waste treatment (removing
intractable particles in oily fluids)– paints (separating solvents from pigments)
Nur Istianah-T.Membrani-2016
ULTRAFILTRATION• to separate a solution; mixture of desirable
and undesirable components • has smaller pores than microfiltration
membranes • driving force → pressure differential (2-10 bars
to 25-30 bars)• used to separate species with pore sizes 10-
1000 Å (103-0.1 microns) • Can be obtained down to a a molecular weight
cutoff (MWCO) level of 1000 Daltons (Da) and up to as high as 1 000 000 Da.
• assymmetric; the pores are small
Nur Istianah-T.Membrani-2016
• wide range of applications :– oil emulsion waste treatment– treatment of whey in dairy industries– concentration of biological macromolecules– electrocoat paint recovery– concentration of textile sizing– concentration of heat sensitive proteins for
food additives – many more …
ULTRAFILTRATION
Nur Istianah-T.Membrani-2016
• wide range of applications in the near future:– ultraflitration of milk– bioprocessing (separation and concentration
of biologically active components)– protein harvesting– refining of oils
ULTRAFILTRATION
Nur Istianah-T.Membrani-2016
• Application in food processing:– concentrate milk prior to the manufacture of dairy
products (the most use), – To concentrate whey to 20% solids or selectively to
remove lactose and salts. – In cheese manufacture, ultrafiltration has advantages
in producing a higher product yield and nutritional value, simpler standardisation of the solids content, lower rennet consumption and easier processing.
ULTRAFILTRATION
Nur Istianah-T.Membrani-2016
• Application in food processing:– concentration of sucrose and tomato paste – treatment of still effluents in the brewing and distilling
industries– separation and concentration of enzymes, other proteins or
pectin– removal of protein hazes from honey and syrups– treatment of process water to remove bacteria and
contaminants (greater than 0.003 m in diameter) (Mackintosh, 1983)
– pre-treatment for reverse osmosis membranes to prevent fouling by suspended organic materials and colloidal materials.
ULTRAFILTRATION
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
NANOFILTRATION• less pore sizes than ultrafiltration membranes• the mass transfer mechanism is diffusion & separate small
molecules from the solution (assymmetric)• NF is• capable of removing ions that contribute significantly to
the osmotic pressure • Can be operated at lower pressures than RO• cellulosic acetate and aromatic polyamide type membranes
(salt rejections; 95% for divalent salts to 40% for monovalent salts)
• can typically operate at higher recoveries; conserving total water usage due to a lower concentrate stream flow rate (advantage over reverse osmosis)
• not effective on small molecular weight organics (e.g.methanol)
Nur Istianah-T.Membrani-2016
NANOFILTRATION
• typical applications:– desalination of food, dairy and beverage products
or byproducts – partial desalination of whey, UF permeate or
retentate as required – desalination of dyes and optical brighteners – purification of spent clean-in-place (CIP) chemicals – color reduction or manipulation of food products – concentration of food, dairy and beverage
products or byproducts – fermentation byproduct concentration
Nur Istianah-T.Membrani-2016
Ion-exchange and electrodialysis: separation methods that remove electrically charged ions and molecules from liquids.
solutes such as metal ions, proteins, amino acids and sugars are transferred from a feed material and retained on a solid ion-exchange material by a process of electrostatic adsorption (i.e. attraction between the charge on the solute and an opposite charge on the ion-exchanger). They can then be separated by washing off the ion-exchanger.
They are constructed using a porous matrix made from polyacrylamides, polystyrene, dextrans or silica.
The applications in food processing include decolourisation of sugar syrups, protein recovery from whey or blood, water softening and dimineralisation and separation of valuable materials such as purified enzymes (Grandison, 1996)
Nur Istianah-T.Membrani-2016
ION EXCHANGE
a liquid feed mixture is separated by partial vaporisation through a non-porous, selectively permeable membrane. Partial vaporisation is achieved by reducing the pressure on the permeate side of the membrane (vacuum pervaporation) or less commonly, sweeping an inert gas over the permeate side (sweep gas pervaporation).
Application:Vacuum pervaporation at ambient temperatures using hydrophilic
membranes is used to dealcoholise wines and beers, hydrophobic membranes are used to concentrate aroma
compounds, such as alcohols, aldehydes and esters,
Nur Istianah-T.Membrani-2016
PERVAPORATION
It produces a vapour permeate and a liquid retentate.
Retentate (liquid)
Permeate (vapor)
Membrane
Feed
Material of membrane
Hydrophilic polymers
Hydrophobic polymers
preferentially permit water permeation
(e.g. poly (vinyl alcohol) or cellulose acetate)
preferentially permit permeation of organic materials.
e.g. Poly (dimethylsiloxane) or poly (trimethylsilylpropyne)
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
The important factors in determining the performance of a membrane
Thickness
Molecular structure
Chemical compositi
on
Flat membranes
Spiral wound membranes
Hollow-fiber membranesVery-small-diameter hollow fibers, the high-pressure feed enters the shell side at one end and leaves at the other end (closed)
Membrane Configurations
Three basic structures are commonly uses for membranes: homogeneous, asymmetric, and composite
Constructed from flat sheet membranes separated by spacer screens, and susceptible to fouling by particulates
Nur Istianah-T.Membrani-2016
20
Flate
Spiral
Hollow
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
Tabel 1. Aplikasi Teknik Separasi Membran pada Pengolahan Produk Pangan
No Teknik Proses Tujuan Proses Pustaka
1 Mikrofiltrasi Penghilangan pektin pada sari buah apel
Zakoer and Mc. Lelan (1993)
2 Ultrafiltrasi Pemurnian isolat protein kedelai Debra and Cheryan (1981)
3 Ultrafiltrasi Penyederhanaan proses produksi sari buah apel
Thomas, et.al. (1986)
4 Ultrafiltrasi Pemisahan komponen kasein Woychik et.,al (1992)
5 Ultrafiltrasi Penurunan kandungan bakteri pada kecap
Tien and Chiang (1992)
6 Ultrafiltrasi & reverse osmosis
Pengembangan berbagai produk tepung protein dari kacang tanah
Lawhon, et., al (1981)
Nur Istianah-T.Membrani-2016
Advantages :
Continuous separation
Low energy requirement
Meet various separation demands
reduce the loss of volatiles or changes to
nutritional or eating quality of food
simple installation with lower labour and
operating costs
Nur Istianah-T.Membrani-2016
Disdvantages :
higher capital costs than evaporation
maximum concentration to 30% total solids
fouling of the membranes (deposition of
polymers), which reduces the operating time
between membrane cleaning.
Nur Istianah-T.Membrani-2016
Movement of molecules through reverse osmosis
membranes is by diffusion and not by liquid flow. The
molecules dissolve at one face of the membrane, are
transported through it and then removed from the
other face. The flow rate of liquid (the ‘transport rate’
or ‘flux’) is determined by the solubility and diffusivity
of the molecules in the membrane material, and by
the difference between the osmotic pressure of the
liquid and the applied pressure.
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016Diffusivity
Membrane thickness
Conceentration and molar volume of solvent
K (ΔP – Δπ )Osmotic pressure
applied pressure
Flux (in kg/h.m2)
J =NA
P(Pa) : trans-membrane pressure, Pf(Pa) : pressure of the feed (inlet),Pr(Pa) : pressure of the retentate (outlet) (high molecular weight fraction) andPp (Pa) : pressure of the permeate (low molecular weight fraction)
The pressure difference across the membrane (the trans-membrane pressure) is found using:
Nur Istianah-T.Membrani-2016
Equations in membrane
................... (1)
Water flux increases with an increase in applied pressure, increased permeability of the membrane and lower solute concentration in the feed stream.
Jw(kg/h) = solvent (water) flux,K(kg / m2.h.Pa) = mass transfer coefficient/permeability const.A(m2) = area of the membrane,Δ P(Pa) = applied pressure andΔπ(Pa) = change in osmotic pressure.
Osmotic pressure is found for dilute solutions using:
π = MRT
Jw = kA (ΔP – Δπ)
Nur Istianah-T.Membrani-2016
................... (2)
................... (3)
M=molarity, T(K), R= 8.314 kPa.m3mol-1K-1
Nur Istianah-T.Membrani-2016
Experimental Osmotic pressure
Larger solutes become concentrated at the membrane surface. The flux is therefore controlled by the applied pressure, and the solute concentrations in the bulk of the liquid and at the membrane surface:
Js= solute fluxc1= concentration of solutes at the membrane c2= concentration of solutes in the liquid
Nur Istianah-T.Membrani-2016
................... (4)Js = kA ln (c1 / c2)
Nur Istianah-T.Membrani-2016
Contoh soal
Hitunglah tekanan osmotic larutan yang mengandung 0.10 mmol NaCl/kg H2O pada suhu 25°C dengan densitas air 997.0 kg/m3.
Penyelesaian:
RTVnMRTm
mVm
kPax 28.494997/1
)15.298)(314.8(102 4
Nur Istianah-T.Membrani-2016
Contoh soal
Jus buah yang mengandung 9% w/w partikel padat (solid) telah diberi perlakuan pre-concentration pada 35°C dengan reverse osmosis untuk kemudian dilakukan ‘concentration’ pada evaporator. Jika tekanan operasi RO adalah 4000 kPa dan koefisien transfer massa sebesar 6.3x10-3 kg.m-2h-1kPa-1, hitung luasan area membran yang diperlukan untuk menghilangkan 5 ton permeate selama 8 jam. (asumsikan mayoritas partikel padat berbentuk sucrose dan konstanta gas universal (R= 8.314 kPa.m3mol-1K-1)
Nur Istianah-T.Membrani-2016
Penyelesaian:Molar concentration (M) = concentration (kg/m3) : molecular weight
M = 90/342 = 264 mol m-3 = 0.264 mol/L
Tekanan osmotic (persamaan 3)
π = 0.264 x 8.314 (35+273) = 676 kPa
Flux (kg/jam feed): J = 5000 kg / 8 jam = 625 kg/jam
Persamaan 2:
625 = 6.3x10-3. A (4000 – 676)
A = 29.9 m2 = 30 m2
Nur Istianah-T.Membrani-2016
Latihan soal
Hitunglah tekanan osmotic larutan berikut pada suhu 25°C dengan densitas air 997.0 kg/m3. (a) Larutan 0.5 mmol NaCl/kg H2O (b) Larutan 1.0 g sucrose/kg H2O (c) Larutan 1.0 g MgCl2/kg H2O
Nur Istianah-T.Membrani-2016
Latihan soal
Sebuah membran cellulose-acetate dengan area 4x10-3 m2 digunakan pada suhu 25°C untuk menentukan konstanta permeabilitas RO larutan garam yang mengandung 12 kg NaCl/m3 (ρ=1005.5 kg/m3) dan dihasilkan produk larutan dengan konsentrasi 0.486 kg NaCl/m3 (ρ=997.3 kg/m3). Flow rate produk adalah 3.84x10-8 m3/s dan tekanan operasi sebesar 56.0 atm. Hitunglah konstanta permeabilitas RO tersebut!Densitas air pada 25°C adalah 997 kg/m3 #Bagaimana pengaruh kenaikan suhu sebesar 30 K pada flow rate produk jika dioperasikan pada tekanan sama!
THANKS FOR YOUR ATTENTION
The best person is one give something useful always
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
Nur Istianah-T.Membrani-2016
Hitunglah tekanan osmotic larutan berikut pada suhu 25°C dengan densitas air 997.0 kg/m3. (a) Larutan 0.5 g mol NaCl/kg H2O (b) Larutan 1.0 g sucrose/kg H2O (c) Larutan 1.0 g MgCl2/kg H2O
Jawaban:(a) = (0.5/58.5)*997*298.15 =